The present invention relates to a process of preparing multi-layered foam articles and to the resulting articles which exhibit a soft, leather-like feel. In a preferred embodiment, the invention relates to seats for transportation vehicles produced by such processes.
The molded foam portion of a seat, particularly seats for transportation vehicles such as automobiles, is generally composed of two or more foams of different hardness. Multi-layered or multi-hardness polyurethane foams are defined as layers of foams of different hardness (load bearing) and/or densities. These foams are usually used to make seat cushions or squabs which have high SAG factors (that is, the ratio of hardness at high deflection to hardness at low deflection) and superior comfort, especially regarding H-point retention (seat occupant""s vertical position).
Various methods are known in the art for preparation of multi-layered polyurethane foams. Such processes are disclosed, for example, in U.S. Pat. No. 3,847,720, U.S. Pat. No. 4,015,041, U.S. Pat. No. 3,887,735, U.S. Pat. No. 4,190,697, EP Patent Publications 251,659 and 279,324 and WO Publication 98/25748. Such methods include applying a liquid mixture of a first polyurethane forming layer into the mold and then pouring, prior to the final curing of the first polyurethane forming layer, a liquid mixture of a second polyurethane forming layer. The two polyurethane layers are then cured. While seats produced by such processes have good wear properties, they fail to measure up to the comfort level expected of some users.
It would be advantageous to produce multi-layered foam articles for use in seats for transportation vehicles and other applications, which are durable and exhibit a high comfort level. It would also be advantageous for such foamed articles to have a durable outer or top layer which is aesthetically and texturally pleasing to the consumer.
The invention is directed to a process for producing multi-layered foam articles, particularly seats for transportation vehicles, such as automobiles, having an elastomeric top layer and a bottom layer. The elastomeric layer is adhered to the bottom foam layer in some areas and not adhered to the bottom foam layer in other areas. The elastomeric top layer may have a grain or pattern to meet individual style requirements.
In a preferred embodiment, the resulting article is defined by an inner zone and one or more raised supports peripheral to the inner zone. In light of its softness and leather-like feel, the resulting article renders a high degree of comfort. In particular, the resulting article has a soft, leather-like feel on its top surface since the elastomeric layer is not completely attached to the bottom foam layer. This is an advantage over the prior art which describes a top elastomeric layer completely attached to the bottom foam layer. The resulting article is cheaper than leather coverings since it is made of less expensive materials.
The process of the invention consists of applying a first formulation capable of forming an elastomeric layer into a mold, applying a release agent to the elastomeric layer in the section of the mold where it is desired to have the elastomer not adhered to the bottom foam layer and then, before the elastomeric forming formulation has cured, pouring into the mold a second formulation capable of producing a foam. After the first elastomeric forming formulation and second formulations have been sufficiently cured, the article is removed from the mold. The portion of the article that is in contact during use with the consumer is the elastomeric layer. The elastomeric layer of the inverted molded article is not attached to the bottom foam layer in the areas where the release agent is applied. The presence of the release agent where the release agent is applied prevents adherence of the foam layer to the elastomeric layer.